Separating apparatus

ABSTRACT

Apparatus for separating two non-miscible liquids of different densities from a mixture thereof, including a vertical cylindrical tank with an inlet at one side and an outlet at the opposite side. External means produces a flow of the mixture into the inlet and of the heavier liquid through the outlet. The tank extends above and below the liquid-air interface to provide a free liquid surface inside the tank. A rotating impeller at the center of the bottom of the tank swirls the liquid in the tank and creates a vortex. The lighter liquid collects in a thick layer at the center of the vortex and is substantially absent from the periphery of the vortex. The lateral outlet carries away the heavier liquid. An outlet for the lighter liquid has an opening submerged in the liquid at the center of the vortex. A pump removes the lighter liquid through this outlet. The separating apparatus may be mounted on a twin hulled vessel and propelled through the water, for the purpose of removing an oil slick from the surface. The inlet for the oil and water mixture is at the bow end of the tank, with the water outlet at the stern end. The oil outlet is provided with a pump for transferring the oil into suitable storage tanks, which may be in the hull or in separate vessels. Means are provided for coordinating the operation of the impeller and the oil pump.

United States Patent [191 Aiello et al.

[ Aug. 21, 1973 1 SEPARATING APPARATUS [76] Inventors: Victor S. Aiello,Glen Cove; Joseph P. Albanese, Long Island City; Robert V. Anderson,Huntington; Frank Platt, Brooklyn, all of N.Y.

221 Filed: June 19, 1970 21 Appl. No.: 47,778

OTHER PUBLlCATIONS Sucking Oil from the Sea", Financial Times, April 6,1970.

Primary Examiner-Frank A. Spear, .lr. AttorneyLester W. Clark, Robert S.Dunham, P. E. Henninger, Thomas F. Moran, Gerald W. Griffin, R. BradleeBoal, Christopher C. Dunham and Robert Scobey [57] ABSTRACT Apparatusfor separating two non-miscible liquids of different densities from amixture thereof, including a vertical cylindrical tank with an inlet atone side and an outlet at the opposite side. External means produces aflow of the mixture into the inlet and of the heavier liquid through theoutlet. The tank extends above and below the liquid-air interface toprovide a free liquid surface inside the tank. A rotating impeller atthe center of the bottom of the tank swirls the liquid in the tank andcreates a vortex. The lighter liquid collects in a thick layer at thecenter of the vortex and is substantially absent from the periphery ofthe vortex. The lateral outlet carries away the heavier liquid. Anoutlet for the lighter liquid has an opening submerged in the liquid atthe center of the vortex. A pump removes the lighter liquid through thisoutlet.

The separating apparatus may be mounted on a twin hulled vessel andpropelled through the water, for the purpose of removing an oil slickfrom the surface. The inlet for the oil and water mixture is at the bowend of the tank, with the water outlet at the stern end. The oil outletis provided with a pump for transferring the oil into suitable storagetanks, which may be in the hull or in separate vessels. Means areprovided for coordinating the operation of the impeller and the oilpump.

9 Claims, 8 Drawing Figures SEPARATING APPARATUS BACKGROUND OF THEINVENTION Many devices have been proposed for separating mixtures of twoliquids, such as oil and water. Many of the proposed devices have beenparticularly intended for removing oil slicks from the surface of theopen sea. The apparatus shown in the Patent to Cornelissen, No.3,348,690 is typical. It comprises a barge having a pair of laterallyextending skimming booms which extend above and below the surface of thewater and guide the oil slick into intakes at the sides of the barge.The liquid received through the intake is pumped into settling tanksinside the barge, where a final separation of the oil and water takesplace. The oil is pumped out of the settling tanks to storage tanks. Thewater is discharged back into the sea.

BRIEF SUMMARY OF THE INVENTION According to the present invention, theseparation of the oil and water is completed before the oil is pumpedinto the pick-up system. This separation is accomplished by directingthe water with a layer of oil floating on it into a vertical cylindricaltank extending above and below the liquid surface. At the bottom of thetank, an impeller maintains the liquid in the tank in rotation about avertical axis, so as to create a vortex substantially at the center ofthe liquid-air interface. The oil appears in this vortex as a layer ofmaximum thickness at the center, and decreasing to substantially zerothickness at the periphery,

A float having a contour symmetrical about a vertical axis is located inthe tank and centers itself in the vortex. The float carries an outletpipe for the oil whose open lower end is submerged in the liquid at thecenter of the vortex. The outlet pipe section carried by the float ispreferably rigid, but the top of it connects to a flexible pipe sectionwhich may move laterally by a limited amount so as to allow the float tofollow lateral movements of the vortex. The pipe is also verticallyextendable, so as to accommodate changes in the liquid level withrespect to the sides of the tank, such as may be occasioned by thefilling of the storage tanks in the hull of the vessel.

DRAWINGS FIG. 1 is a starboard elevation of a vessel carrying aseparating apparatus in accordance with the invention. FIG. 2 is a bowelevation of the vessel of FIG. 1.

FIG. 3 is a sectional view of the vessel of FIG. 1, taken along the line33 of FIG. 1.

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1.

FIG. 5 is a fragmentary view, similar to the central portion of FIG. 4,showing a modified form of float.

FIG. 6 is a plan view of the bottom of the separator tank, showing amodified form of impeller.

FIG. 7 is a sectional view on the line 77 of FIG. 6.

FIG. 8 is an electrical wiring diagram showing a circuit for energizingthe impeller motor and the pump motor.

DETAILED DESCRIPTION The vessel in FIG. 1 includes twin hulls 1connected by a deck 2, which is supported on the upper surface of thehulls. The deck 2 is generally U-shaped when viewed in plan, as bestseen in FIG. 3. A bridge 3 connects the midpoints of the twolongitudinal sides of the deck. The bridge 3 includes a horizontal beam3a, which supports by means not shown, a vertical, generally cylindricalseparator tank 4. The term vertical, generally cylindrical tank isintended to define a tank such as that shown in the drawings (see FIG.3), in which the bow wall and the stern wall are vertical sections ofcylinders, not necessarily of the same radius, and having vertical axeswhich are not necessarily coincident. The bow end of the tank, appearingat the right in FIG. 1, is provided with a multiplicity of perforations4a, which serve as an inlet for the water through which the vessel ismoving. To avoid excessive disturbance of the vortex by the motion ofthe vessel through the water, the openings created by the perforationsmust not exceed 50 percent of the total slotted area. Also, for greatestefficiency, the angle in a horizontal plane subtended by the arc of thetotal perforated area, when viewed from above, should be approximatelyVertical slots may be used instead of perforations. Suitable propulsionmeans for the vessel may be provided, such as an engine 35, driving apropeller 36 (see FIG. 3). Alternatively, the vessel may be towed bymeans of stanchions 37.

The openings 4a are arranged to extend both above and below the waterlevel, so that variations in the draft of the vessel can beaccommodated. Any liquid floating on the surface of the water is carriedinto the tank 4 by the motion of the vessel. The perforated front wallof the tank also serves as a trash grill to keep floating solid objectsout of the tank 4. The bottom of the tank 4 is closed. The tank 4 may bemade of magnetic material, e.g., steel. At the center of the bottom ofthe tank, there is provided an opening 4b, which is closed by a plate 5of non-magnetic material. On the underside of the plate 5 is mounted amotor 6, which may be an electric motor is a suitable watertighthousing. The motor 6 drives an impeller 7 mounted on the upper side ofthe plate 5 through a suitable magnetic coupling, to avoid the necessityof a rotating shaft with a packed seal at the bottom of the tank. Therotation of the impeller 7 creates a vortex in the surface of the liquidat the center of the tank. The oil-water surface is shown in FIG. 4 at 8and the oil-air surface is shown at 9. Because of the difference indensity of the oil and water, the thickness of the oil layer at thecenter of the tank is substantially greater than the thickness of theoil layer at the edges of the tank. Hence, there is formed a pool of oilhaving substantial depth at the center of the tank.

The speed of the impeller should be slow enough to prevent turbulenceanywhere in the tank. A speed of two to three rotations per second hasbeen found satisfactory. An impeller diameter between about onefourth toabout one-third of the tank diameter has also been found satisfactory.

A float 10 shown as having a toroidal contour is symmetrical about avertical axis and is provided with spokes ll connecting the toroidalpart of the float to a conduit 12 which extends vertically along theaxis of the float, and has its lower end submerged in the central poolof oil in the vortex. The upper end of the conduit l2 communicates witha flexible conduit section 13, shown as having a corrugated wall, whichallows it to move freely through a limited distance in any lateraldirection, so as to accommodate changes in the position of the vortex inthe tank.

The corrugated section 13 is also vertically extendable, so as toaccommodate changes in the liquid level in the tank with respect to thehulls 1. When the hulls l are being used for oil storage, as shown, thewater line on the outside of the hull may vary considerably between theempty tank condition and the full tank condition. The expandable pipe 13is provided to accommodate this situation, and allow the bottom inletend of the pipe 12 to remain in the oil pool at the center of thevortex, regardless of how high or low the vessel is riding in the water.

The upper end of the corrugated conduit section 13 is connected toanother rigid conduit 14, which leads to the inlet of a pump 15, whichmay be driven by an electric motor 24. The pump 15 has a dischargeconduit 16 leading through a flexible hose 17 to an inlet 18communicating with the interior of one of the hulls 1. Alternatively,conduit 16 may be connected by suitable valving (not shown) to aflexible oil storage bag which may be floating in the water. After thebag is filled with oil, it is sealed and either left for later pickup ortowed along. A quantity of storage bags may be carried on board. The twohulls 1 are connected near their bottoms by a pipe 20 which maintainsthe oil levels in the two hulls substantially equal. Inside pipe 20,baffles (not shown) are provided which limit the rate of transfer of oilbetween hulls 1 during swells.

The stern end of the tank 4 is provided with a plurality of openings 4c,similar to those at the bow end 4a, which serve as water outletopenings. The openings 40 may be located both above and below the waterline, as shown, or may be only below the water line, so that the sternwall of the tank then serves as a skimmer to prevent oil from escapingover the back side of the vortex. It has been found that for most oilslicks, which are not very thick (e.g., about 0.12 inch), it does notmatter whether the outlet openings 40 extend above the water line. It isconceivable, however, that when operating with an oil layer ofsubstantial depth, it may be desirable to have all the outlet openings4c below the liquid level.

The stern side of the tank also serves as a trash grill to keep floatingobjects out of the tank.

A baffle 21, perforated in a manner similar to apertures 4a and 4c, ofgenerally arcuate cross-section, extends vertically from the bottom ofthe tank, and is located inside the tank and aligned with the inletapertures 4a. The purpose of the baffle 21 is to avoid excessivedisturbance of the vortex by motion of the vessel through the water.

FIG.

This figure illustrates a modified contour of the float. The float ofFIGS. 3 and 4 is replaced in FIG. 5 by a spherical float 31a. The pipesection 12 extends through the vertical axis of the spherical float 31aand has its inlet opening at the bottom of the float.

FIGS. 6-7

These figures illustrate a modified form of impeller. Instead of being asimple bar impeller as shown at 7 in FIGS. 3 and 4, the impeller 22 ofFIGS. 6 and 7 has a plurality of spiral blades extending outwardly froma central hub affixed to a shaft 23 which passes through a suitablesealed opening in the bottom of the tank 4, and is driven by an impellermotor 6.

FIG. 8

This figure illustrates an electrical circuit for energizing theimpeller motor 6 and the pump motor 24. The source of energy is shown asa battery 25. The impeller motor may be started by closing a switch 26.After the switch 26 is closed, the pump motor may be started by closinga switch 27. Note that the pump motor cannot be started unless theimpeller motor 6 is running, although the two can be startedsimultaneously. If desired, a suitable time delay can be added to switch27, to make sure that the impeller comes up to a vortexforming speedbefore the pump motor 24 is started.

In some cases it may be desirable to add a sensing device, such as aconductivity measuring device, at the inlet of the conduit 12, andconnecting this sensing device to suitable apparatus for controlling thepump motor 24. The pump motor 24 may then be prevented from operatingunless there is oil present at the inlet opening of the conduit 12.

While it is preferred to pump the oil into the hulls l, as shown, orinto the collapsible storage bags, as described, the oil mayalternatively be pumped into a container carried by an adjacent barge orother craft.

The separator apparatus according to the invention substantiallycompletely separates the oil from the water and delivers substantiallypure oil to the storage tank. It is not contended that the oil sodelivered is I completely pure, but there is little or no waterentrained with it, as compared with the prior art oil separatingdevices.

The efficiency of the separation process is further enhanced by theaddition of a skimmer 38, shown in FIG. 3. The skimmer 38 consists of awooden, plastic or hollow metal bar, anchored to the walls of the tankin a manner such as to float on the liquid surface. When there is verylittle oil in the tank, surface tension in the oil causes the oil toglobulate on the surface instead of forming a continuous film. Theseglobules might drift out of the tank through the water outlet 40 orcirculate indefinitely unless prevented by skimmer 38 which deflects theglobules, causing the oil to be drawn into the vortex. The efficiency ofthe process is thereby increased from approximately 93 percent without askimmer to 99 percent with the addition of the skimmer.

As shown, the skimmer bar 38 is pivotally connected at one end 380 tothe side of the tank where the liquid is moving toward the stern. Theother end 38b is con nected by a chain 39 to the other side of the tank.Both ends of the bar may be connected to accommodate variations in thedraft of the vessel, for example, by means of chains, or otherwise.

Our separator apparatus is not limited in its utility to the separationof oil and water, but may be used to separate any two non-miscibleliquids of different densities. It is not necessarily used on a vessel,nor is it necessarily used for removing oil slicks from the surface ofthe open sea. The tank 4 can be mounted on dry land and supplied with acombination of non-miscible liquids of different densities at its inletside and would successfully separate the two liquids. It is necessarythat the two liquids be non-miscible to the extent that they tend toseparate by gravity when a mixture of them is allowed to stand.

Another significant difference of our apparatus as compared to priorapparatus is the fact that the heavier liquid (water) is never liftedabove the sea. Also, other devices do not operate well in a realisticsea environment.

We claim:

1. Apparatus for separating two liquids of different densities from amixture thereof, including:

a. a vertical, generally cylindrical separator tank having an inlet in aside wall of the tank for said mixture of two liquids;

b. lateral discharge outlet means for the heavier liquid in a side wallof the tank opposite the inlet and having sufficient capacity tomaintain the liquid level below the top of the tank;

c. an impeller at the center of the bottom of the tank;

d. means for rotating said impeller to create a vortex at the surface ofthe liquid in the tank, said vortex being spaced vertically above theimpeller;

e. an outlet for the lighter of said two liquids having an openingsubmerged in the liquid at the center of the vortex, said outlet for thelighter liquid comprising:

l. a float within the tank and having a contour symmetrical about avertical axis and aligned with the axis of the impeller; and

2. a conduit fixed to the float and extending along the vertical axisthereof and communicating with said submerged opening, said float beingeffective to centralize in the vortex the outlet for the lighter liquid.

2. Apparatus as in claim 1, in which:

a. said conduit fixed to the float extends upwardly from said submergedopening;

b. said outlet for the lighter liquid further comprises: 1. a flexibleconduit section connected to the upper end of the conduit fixed to thefloat; and

2. a conduit fixed to the top of the tank and connected to the upper endof said flexible conduit.

3. Apparatus as defined in claim 1, in which said float has a toroidalcontour.

4. Apparatus as defined in claim 1, in which said float has a sphericalcontour.

5. Apparatus for separating two liquids of different densities from amixture thereof, including:

a. a vertical, generally cylindrical separator tank having an inlet in aside wall of the tank for said mixture of two liquids;

b. lateral discharge outlet means for the heavier liquid in a side wallof the tank opposite the inlet and having sufficient capacity tomaintain the liquid level below the top of the tank;

c. an impeller at the center of the bottom of the tank;

d. means for rotating said impeller to create a vortex at the surface ofthe liquid in the tank, said vortex being spaced vertically above theimpeller;

e. an outlet for the lighter of said two liquids having an openingsubmerged in the liquid at the center of the vortex; and

f. skimmer means floating on the liquid between the vortex and thelateral discharge outlet means, and effective to deflect floating massesof the lighter liquid away from the lateral discharge outlet means andtoward the 6. A vessel for for skimming a light, non-watermiscibleliquid from a surface of a body of water, including:

a. hull means;

b. propulsion means for advancing the hull means through the body ofwater;

c. a vertical cylindrical separator tank supported by said hull meansand extending above and below the water level, said tank including:

1. an inlet at the bow end of the tank and extending above and below thewater level;

2. an outlet at the stern end of the tank and at least partly below thewater level;

3. means for creating a vortex at the surface of the liquid in saidtank;

4. light liquid outlet means having an opening submerged in the liquidat the center of said vortex;

d. a pump connected to said light liquid outlet means;

e. a motor for driving said pump; and

f. sensing means located at the opening of said light liquid outletmeans and effective to distinguish between said light liquid and water;and

g. means controlled by said sensing means preventing energization of themotor unless the light liquid is present at the outlet opening.

7. A vessel for skimming a light, non-water-miscible liquid from asurface of a body of water, including:

a. hull means;

b. propulsion means for advancing the hull means through the body ofwater;

0. a vertical, generally cylindrical separator tank supported by saidhull means and extending above and below the water level, said tankincluding:

1. an inlet in the bow wall of the tank and extending above and belowthe water level;

2. an outlet in the stern wall of the tank and at least partly below thewater level;

3. means for creating a vortex at the surface of the liquid in saidtank;

4. light liquid outlet means having an opening submerged in the liquidat the center of said vortex; and

d. skimmer means floating on the liquid between the vortex and the sternoutlet and effective to deflect floating masses of the lighter liquidaway from the stern outlet and toward the vortex.

8. A vessel for skimming a lighter-than-water, nonwater-miscible liquidfrom a surface of a body of water, including:

a. hull means;

b. propulsion means for advancing the hull means through the body ofwater;

c. a vertical generally cylindrical separator tank supported by saidhull means and extending above and below the water level, said tankincluding:

1. a vertically extending bow wall of partcylindrical form having inletopenings therein both above and below the water level through whichopenings water and a lighter liquid floating thereon may enter the tankwithout substantial change in level;

2. a vertically extending stern wall of partcylindrical form having adifferent radius of curvature than the bow wall, said stern wall havingoutlet openings therein, said outlet openings being at least partlybelow the water level, through which outlet openings water may flow fromthe tank without substantial change in level;

3. means within the tank and spaced from the bow and stem walls forcreating a vortex at the surface of the liquid in said tank;

b. a baffle within the tank and concentric with said axis, said bafflebeing aligned with said inlet openings and the vortex creating means,and effective to shield the vortex from disturbance by liquid enteringthe tank.

1. Apparatus for separating two liquids of different densities from amixture therEof, including: a. a vertical, generally cylindricalseparator tank having an inlet in a side wall of the tank for saidmixture of two liquids; b. lateral discharge outlet means for theheavier liquid in a side wall of the tank opposite the inlet and havingsufficient capacity to maintain the liquid level below the top of thetank; c. an impeller at the center of the bottom of the tank; d. meansfor rotating said impeller to create a vortex at the surface of theliquid in the tank, said vortex being spaced vertically above theimpeller; e. an outlet for the lighter of said two liquids having anopening submerged in the liquid at the center of the vortex, said outletfor the lighter liquid comprising:
 1. a float within the tank and havinga contour symmetrical about a vertical axis and aligned with the axis ofthe impeller; and
 2. a conduit fixed to the float and extending alongthe vertical axis thereof and communicating with said submerged opening,said float being effective to centralize in the vortex the outlet forthe lighter liquid.
 2. a conduit fixed to the top of the tank andconnected to the upper end of said flexible conduit.
 2. Apparatus as inclaim 1, in which: a. said conduit fixed to the float extends upwardlyfrom said submerged opening; b. said outlet for the lighter liquidfurther comprises:
 2. a conduit fixed to the float and extending alongthe vertical axis thereof and communicating with said submerged opening,said float being effective to centralize in the vortex the outlet forthe lighter liquid.
 2. a vertically extending stern wall ofpart-cylindrical form having a different radius of curvature than thebow wall, said stern wall having outlet openings therein, said outletopenings being at least partly below the water level, through whichoutlet openings water may flow from the tank without substantial changein level;
 2. an outlet in the stern wall of the tank and at least partlybelow the water level;
 2. an outlet at the stern end of the tank and atleast partly below the water level;
 3. means for creating a vortex atthe surface of the liquid in said tank;
 3. means for creating a vortexat the surface of the liquid in said tank;
 3. Apparatus as defined inclaim 1, in which said float has a toroidal contour.
 3. means within thetank and spaced from the bow and stern walls for creating a vortex atthe surface of the liquid in said tank;
 4. light liquid outlet meanshaving an opening submerged in the liquid at the center of said vortex;and d. skimmer means floating on the liquid between the vortex and thestern outlet and effective to deflect floating masses of the lighterliquid away from the stern outlet and toward the vortex.
 4. outlet meansfor the lighter liquid only having an opening submerged in the liquid atthe center of said vortex.
 4. Apparatus as defined in claim 1, in whichsaid float has a spherical contour.
 4. light liquid outlet means havingan opening submerged in the liquid at the center of said vortex; d. apump connected to said light liquid outlet means; e. a motor for drivingsaid pump; and f. sensing means located at the opening of said lightliquid outlet means and effective to distinguish between said lightliquid and water; and g. means controlled by said sensing meanspreventing energization of the motor unless the light liquid is presentat the outlet opening.
 5. Apparatus for separating two liquids ofdifferent densities from a mixture thereof, including: a. a vertical,generally cylindrical separator tank having an inlet in a side wall ofthe tank for said mixture of two liquids; b. lateral discharge outletmeans for the heavier liquid in a side wall of the tank opposite theinlet and having sufficient capacity to maintain the liquid level belowthe top of the tank; c. an impeller at the center of the bottom of thetank; d. means for rotating said impeller to create a vortex at thesurface of the liquid in the tank, said vortex being spaced verticallyabove the impeller; e. an outlet for the lighter of said two liquidshaving an opening submerged in the liquid at the center of the vortex;and f. skimmer means floating on the liquid between the vortex and thelateral discharge outlet means, and effective to deflect floating massesof the lighter liquid away from the lateral discharge outlet means andtoward the
 6. A vessel for for skimming a light, non-water-miscibleliquid from a surface of a body of water, including: a. hull means; b.propulsion means for advancing the hull means through the body of water;c. a vertical cylindrical separator tank supported by said hull meansand extending above and below the water level, said tank including:
 7. Avessel for skimming a light, non-water-miscible liquid from a surface ofa body of water, including: a. hull means; b. propulsion means foradvancing the hull means through the body of water; c. a vertical,generally cylindrical separator tank supported by said hull means andextending above and below the water level, said tank including:
 8. Avessel for skimming a lighter-than-water, non-water-miscible liquid froma surface of a body of water, including: a. hull means; b. propulsionmeans for advancing the hull means through the body of water; c. avertical generally cylindrical separator tank supported by said hullmeans and extending above and below the water level, said tankincluding:
 9. A vessel as in claim 8, in which said bow and stern wallshave a common vertical axis, and including: a. an impeller in saidvortex creating means rotatable about said axis; and b. a baffle withinthe tank and concentric with said axis, said baffle being aligned withsaid inlet openings and the vortex creating means, and effective toshield the vortex from disturbance by liquid entering the tank.